Hi - please bare with me as there is some background to this story.

My house (in the UK) is built on very sandy soil. Every time I dig over
the borders, I pull out lumps of sandstone sometimes bigger than house
bricks. 3 years ago I laid new turf, front and back. In preparation I
dug over the entire site removing all sandstone / building material. I
dug in some compost and applied some growmore, then prepared the area
and laid the turf.

For the first year or so the lawns were great. As the years have gone
by, the front lawn especially (which spends most time in the sun) now
has brown and completely bare patches. I always apply weed and feed in
the spring and use a lawn rake and apply autumn feed in the autumn.

Having read about the problems caused by compaction, I tried to aerate
the lawn with a garden fork, however the ground is so hard that this is
impractical. I decided that a power drill and 45cm masonry bit would be
more appropriate. Having tested this on a small area, I can see that in
the brown/bare areas I'm pulling up sandstone through the flutes of the
drill and yet the green areas are much easier to 'drill' and remove
soil.

My question is; given that it's beyond what I'm prepared to do to
completely remove the lawns and replace them, would anyone like to
comment on whether I would be wasting my time aerating the entire lawns
in this way, when there is obvious sandstone underneath?

The problem is too acute to simple part the turf and lift out the
offending objects.